基于实时应变监测的钢筋混凝土梁疲劳损伤评估特征指标研究

Research on fatigue damage evaluation characteristic index of reinforced concrete beams based on real-time strain monitoring

为对服役钢筋混凝土梁进行疲劳安全状况评估,进行了基于实时应变监测的疲劳损伤评估特征指标研究。通过"AIT"运算与"傅里叶转换"实现真实响应数据的提取与验证及应力峰值统计等一系列推导,提出了钢筋混凝土梁实时有效疲劳应力、实时疲劳残余应变及实时疲劳剩余刚度的计算表达式。将实时有效疲劳应力、实时疲劳残余应变、实时疲劳剩余刚度作为钢筋混凝土梁疲劳安全评估的特征指标,规定三者同时分别小于各自极限值时,认为结构处于安全状态,反之,结构处于疲劳危险状态。最后,归纳了钢筋混凝土梁疲劳损伤评估特征指标应用流程,并结合实际算例进行了验证分析。

In order to evaluate the fatigue safety status of reinforced concrete beams in service, the study on the characteristic indexes of fatigue damage evaluation based on strain monitoring was carried out. The calculation expressions of real-time effective fatigue stress, real-time fatigue residual strain and real-time fatigue residual stiffness of reinforced concrete beams were proposed by a series of derivations such as the "AIT"calculation and "Fourier transformation" to achieve the extraction and verification of real response data and stress peak statistics. Real-time effective fatigue stress, real-time fatigue residual strain and real-time fatigue residual stiffness were taken as the characteristic index of fatigue safety evaluation of reinforced concrete beams. It is stipulated that the structure is considered to be in a safe state when the three indexes are less than their respective limit values at the same time, on the contrary,the structure is in a fatigue dangerous state. Finally, the application process of the evaluation characteristic index was summarized and verified by practical examples.